Products are commonly shipped as stacks of cargo on pallets placed in the cargo space of an enclosure such as a truck trailer or container. After placing the cargo in the cargo space, it is generally necessary to support the cargo in the cargo space to prevent damage due to shifting.
Common practice is to position two rows of cargo on pallets, each row extending from the front to the rear of the container. The space between the rows should contain braces to prevent shifting as described above.
“Dunnage bags”, large inflatable bags made of paper or other synthetic material with an air tight plastic liner, have been used to prevent the shifting of cargo during transportation. These bags are placed in the space between the cargo and the walls of the container or between neighboring rows of pallets holding cargo and then inflated. The bags are typically inflated to a pressure of not more than 1½ to 2 pounds per square inch (psi). When the cargo arrives at its destination and prior to unloading, the bags are punctured and discarded.
The problem of damage to cargo during transport has such a commonality and severity that the American Association of Rail Roads has adopted standardized requirements for an acceptable protection system.
These requirements for dunnage bags include an “80% footprint” where a footprint is the area of contact of the interface between the wall of the cargo and the bag. This specification satisfies the two requirements that the interface of the bag exert sufficient force over a broad area of the bag to support the product without crushing the cargo such as when the cargo might be bags of fruit.
The A.A.R.R. has also developed a uniform testing procedure that any shipping system must pass in order that the participating company receive the required approval from that Association to apply that system as a basis for its shipping procedure.
The test, referred to herein as the AARR test, incorporated by reference into this specification, is described as follows:    1. A first railcar, loaded with 45,000 pounds, is positioned on a railroad track.    2. Additional railcars having a total weight of 275,000 pounds are accelerated to a speed of 3 miles per hour and caused to slam into the first car.    3. This procedure is repeated a total of 3 times at speeds of 6 miles per hour each time.    4. The spacers are examined to determine any damage that has occurred to the spacers such as rupture of dunnage bags, etc. The amount of movement is measured to determine the effetiveness of the air bags.
Various embodiments of dunnage bags have been disclosed for addressing requirements of dunnage bags.
U.S. Pat. No. 3,427,995 to Stafford discloses an inflatable dunnage bag system positioned between cargo and the end bulkheads of railroad cars. This disclosure does not address the problem of filling space between rows of pallets parallel to the track.
U.S. Pat. No. 4,136,788 discloses a dunnage bag made of layers of paper with flaps extending from the ends of the ply joined to the other wall. This invention suitable only where large overall thickness is required for extra protection, and the “pinched end of the bag results in diminished contact (footprint) can be tolerated.
U.S. Pat. No. 4,553,887 to Reeves discloses a dunnage bag made of triangular sheets of kraft paper lined with polyethylene.
U.S. Pat. No. 4,591,519 to Liebel discloses an airbag for bracing made of a stiff paperboard having vertical stiffness when uninflated.
U.S. Pat. No. 5,042,663 to Heinrick discloses joinable inflatable bladders for packaging.
U.S. Pat. No. 5,288,188 to Vanes discloses a dunnage bag constructed of welded rectangular sheets.
U.S. Pat. No. 5,372,396 to Nahmen discloses a cargo bed liner with side panels pivotally attached.
U.S. Pat. No. 5,431,525 to Sansone et al discloses a dual air bladder air bag.
U.S. Pat. No. 5,693,163 to Hoover et al discloses a method for making inflated dunnage bags “on site” including unrolling a folded sheet and sealing step.
U.S. Pat. Nos. 5,868,534 and 5,788,438 to Boshorn et al discloses a sealed bag inserted into a paper tube.
U.S. Pat. No. 5,908,275 to Howlett discloses an inflatable bag comprising an inflatable inner bladder surrounded by a pair of paper plies.
None of the systems dunnage bags (inflated to 3 psi disclosed in the prior art provide a footprint that is greater than 80% when the space between the parallel pallets is greater than 12 inches. This is because the bags swell toward the ceiling. When the space is greater than 12 inches, an attempt to inflate the bag up to the 3 psi limit results in the bag not having enough surface area coverage against the carge and therefore not exerting enough force on the product.
Accordingly, the present practice for filling spaces having widths greater than twelve inches, is to occupy the additional space with “fillers”. Sheets of “honey comb” panel are commonly used for such purposes. However, the use of filler panels presents a number of inconveniences including storage of the panel when not in use and the inconvenience associated with installing and removing the filler panels when loading and unloading the cargo space and extremely high cost of the fillers.
Rigid collapsible braces have been disclosed for supporting cargo in cargo space. For example, U.S. Pat. No. 4,236,854 discloses a brace having side rails and extensible side arms.
U.S. Pat. No. 4,473,331 to Wisecarver discloses a foot assembly and extensible element with lever locking member.
U.S. Pat. No. 5,181,815 to Haberkorn discloses a collapsible bracing structure and rotatable latches for releasing.
U.S. Pat. No. 6,627,488 B2 to Elze et al. discloses a dunnage bag with an outer mesh covering. The mesh bag is comprised of mesh panels stitched together so that the bag, when inflated, has a “mattress” shape. This shape ameliorates the ballooning problem and provides a greater footprint so that the bag with mesh cover can be used in spaces between cargo stacks that are greater than 80%.
However the mesh outer bag is comparatively expensive compared to paper. Furthermore, paper has an additional advantage in that indicia such as advertising can be printed on the bag.
In view of the above, there continues to be intense interest in improving the dunnage bags and systems presently on the market and disclosed above in terms of reducing expense and inconvenience for filling space between rows of pallets with product where the vertical walls of cargo are spaced by more than twelve inches.